Preparation of novel esters of betahydroxy carboxylic acids by the reaction of beta-lactones with phenols



F'atented Oct. 17, 1 956 UNITED STATES PATENT OFFICE PREPARATION oF NOVEL ESTERS F RETA- HYDROXY CARBOXYLIC ACIDS BY THE REACTION OF BETA-LACTONES PHENOLS WITH Warren L. Beears, Cleveland, Ohio, assignor to The B. F. Goodrich Company, New York, N. Y., a corporation of New York No Drawing. Application April 8, 1948,

Serial No. 19,896

14 Claims.

This invention relates to the preparation of novel esters of beta-hydroxy carboxylic acids, particularly aryl hydracrylates, and pertains more specifically to the preparation of such compounds by the reaction of a phenol and a betalactone.

It is disclosed in U. S. Patent 2,356,459 to Frederick E. Kiing that beta-lactones, that is lactones or inner esters of beta-hydroxy carboxylic acid is obtained when a beta-lactone is reacted with a phenol inthe absence of added materials, or in the presence of an inert organic diluent, or in the presence of an aqueous solution of a base so as to form a salt of the phenol.

I have now discovered that when a beta-lactone is reacted with a phenol in the presence of a catalytic amount of a strong mineral or inorganic acid, reaction occurs at the beta-carbon atom of the beta-lactone to form an aryl ester of a betahydroxy carboxylic acid; and that this reaction provides a convenient and economical method for preparing numerous useful organic compounds which have not heretofore been prepared.

The novel compounds of this invention possess the general formula Lt it wherein Ar is an aryl hydrocarbon radical having its connecting valence on a nuclear carbon atom,

each R is hydrogen or an alkyl, aryl or cycloalkyl radical containing from 1 to 6 carbonatoms, and

Strong mineral Patent Number 2,449,991, that a beta-aroxy cari 2 wherein Ar and R have the meaning set forth hereinabove.

The compounds of the above general formula wherein n is 1, are prepared by a secondary reaction involving the self-alcoholysis of the ester first formed by the reaction of the phenol with the beta-lactone. This secondary reaction, which occurs simultaneously with the primary reaction, may be represented as follows:

RR R

Strong mineral RR RR R Ee 0 011 ArOH 0 II 0 wherein Ar and R are the same as above.

In carrying out the reaction, a preferred pro- "cedure involves first adding the strong mineral acid catalyst, such as sulfuric acid, hydrochloric acid, phosphoric acid and the like, (preferably in catalytic amounts of approximately 1% by weight based on the weight of the beta-lactone, although amounts as small as 2% or smaller and as high as 4% or even higher may be used advantageous- 1y), to the phenol, and then adding the betalactone to the phenol-acid mixture with agitation. However, other procedures such as addition of the acid catalyst to a mixture of the phenol and the lactone may also be used. The reaction may also be conducted in an inert solvent or diluent such as hexane, benzene, carbon tetrachloride or I the like or even water, although the use of such solvent or diluent is not necessary for the reaction to occur.

In order to recover the reaction products from the reaction mixture, the mineral acid catalyst is neutralized by .the addition of a basic material such as an alkali metal alkoxide, inorganic base or other basic substance after which the excess of the phenol, if any, is removed preferably by distillation at reduced pressures. At this point small quantities of solid material, believed to be beta-lactone polymer and resulting from side reactions, may be present and can be easily removed by filtering. The residue is then preferably extracted with an organic solvent such as ether, benzene, and the like and the extract distilled, although, if desired, the residue itself may be distilled at reduced pressures to obtain the products.

: Compounds resulting from the primary and secondary reactions described above are conveniently separated from one another during the distillation. j

'acid;

By controlling the reaction time the proportionate amounts of the products obtained from the primary and secondary reactions can be conveniently controlled. For example when reacting beta-propiolactone with a phenol, highest amounts of aryl hydracrylate are obtained when the time of reaction is relatively short since the secondary reaction of self-alcoholysis is substantially slower than that of the primary reaction to form the aryl hydracrylate. When the reaction time is increased substantially higher yields of the secondary reaction product, that is, a beta- (carbarcxy) alkyl hydracrylate, are obtained. Thus, by selecting the proper reaction time, the desired amount of either reaction product can be obtained.

The quantities of the phenol and the betalactone used in the reaction are not critical and may be varied widely. The reactants may be brought together in equimolecular proportions (the quantities theoretically required for the reaction), although it is desirable that an excess of the phenol be utilized. Thus a phenol-betalactone ratio of from 3:1 to 6:71 is preferred although the ratio may be as low as 1:1 or as high as 811 or even higher.

Other conditions for the reaction such as temperature and pressure are also not critical. Highest yields of the desired products are generally obtained when temperatures of from 30 C. to 70 C. and atmospheric pressure are utilized. However, temperatures as low as C. or lower or as high as 100 C. or even higher are also operative.

Any desired phenol of the formula ArOH wherein Ar is an aryl hydrocarbon radical may be used to react with the beta-lactones. Included in this class of phenols are phenol itself, cresols, Xylenols, o, m and p-hydroxy styrenes, cumenol, naphthols, monc-hydroxy diphenyls, mono-hydroxynaphthalenes, mono-hydroxy anthracenes, mono-hydrcxy diand triphenyl methanes and the like.

' Beta-propiolactone, the simplest possible betalactone, is the preferred beta-lactone for use in this invention because of the ease with which it reacts with phenols to produce aryl hydracrylates and because of its low cost. However, other beta-lactones of the general formula,

wherein each R is a member of the class consisting of hydrogen and alkyl, aryl and cycloalkyl radicals containing fewer than 7 carbon atoms may be used. Included among the beta-lactones of this general class are saturated aliphatic betalactones such as beta-butyrolactone, which gives aryl esters of beta-hydroxy butyric acid; betaisobutyrolactone, which gives aryl esters of betahydroxy isobutyric acid; beta-valerolactone, which gives aryl esters of beta-hydroxy valeric acid; beta-isovalerolactone, which gives aryl esters of beta-hydroxy isovaleric acid; beta-ncaprolactone, which gives aryl esters of betahydroxy caproic acid; alpha-ethyl-beta-propiolactone, which gives aryl esters of alpha-ethyl beta-hydroxy propionic acid; alpha-isopropylbeta-propiolactone, which gives aryl esters of alpha-isopropyl beta-hydroxy propionic acid; alpha-butyl-beta-propiolactone, which gives aryl esters of alpha-butyl-beta-hydroxy propiom'c alpha-methyl-beta-butyrolactone, which gives aryl esters of alpha-methyl-beta-hydroxy butyric acid; alpha-ethyl-beta-butyrolactone, which gives aryl esters of alpha-ethyl-beta-hydroxy butyric acid, and the like.

Beta-lactones containing cycloalkyl and aryl substituents such as beta-cyclohexyl-beta-propiolactone, beta-phenyl-beta-propiolactone, al-

pha-phenyl-beta-propiolactone and the like may.

also be used to produce aryl esters of the corresponding beta-hydroxy carboxylic acids.

In order further to illustrate the invention the following specific examples are set forth but it is to be understood that the invention is not limited thereto. All parts are by weight.

Example I 288 parts (4 moles) of beta-propiolactone are added to 2,256 parts (24 moles) of phenol and 4 parts of concentrated sulfuric acid contained in a flask supported in a constant temperature bath and the reaction mixture is heated at 46 C. for a period of 6 hours. 6.2 parts (40%) excess of sodium methoxide are added to neutralize the acid catalyst and the excess phenol is removed under a reduced pressure of 20 mm. The residue is then poured into ether and 2% parts (8.3%) of solid material are filtered ofi. The ether solution is then extracted with a saturated sodium bicarbonate solution. The ether solution is dried over anhydrous sodium sulfate and the ether removed at reduced pressure. The residue remaining is distilled in a short path still whereupon 213 parts of substantially pure phenyl hydracrylate, B. P. 42-45 C./ .0005 mm. are obtained.

A second fraction, 226 parts, B. P. 92 to 96 C./ 0.6 mm. is identified as beta-(carbophenoxy) ethyl hydracrylate.

Example II Example I is repeated except that the reaction time is reduced to one hour. 332 parts (50) of phenyl hydracrylate and 156 parts (32.8%) of beta-(carbophenoxy) ethyl hydracrylate, B. F. 92 to 96 C./0.6 mm. are obtained.

Example III 282 parts (3 moles) of phenol and 0.5 part of concentrated sulfuric acid are placed in a flask and '72 parts (1 mole) of beta-propiolactone are added with constant stirring. The temperature of the reaction mixture is maintained at 50 C. during the addition of the beta-propiolactone and for ten minutes thereafter. 8.8 part of dium methoxide are then added to neu ralize the catalyst and the excess phenol is removed by distillation at 23 mm. The residue is poured into ether and 8.5 parts of solid material are filtered off. The ether solution is washed with sodium bicarbonate solution and the ether layer dried over anhydrous'sodiurn sulfate. The sodium sulfate is removed by filtering and the ether removed at reduced pressure- The residue is distilled and 66 parts (39.8) of phenyl hydracrylate (B. P. to 45 O./.0O05 mm.) and a 37% yield of beta- (car bophenoxy) ethyl hydracrylate are obtained.

Example IV 324 parts (3 moles) of ortho-cresol and 0.5 part of concentrated sulfuric acid are placed in a reaction'fiask fitted with stirr er, condenser and excess ortho-cresol is removed at 84% C. and a pressure of 16' mm. The residueis poured'into ether, whereupon a very small amount of resinous, gummy precipitate (apparently beta-pro- V .that'the lactone contains from '3 to G'carbori piolactone polymer) is formed. The precipitate I is removed by filtering. The ether filtrate is washed with a saturated sodiumbicarbonate solution and with water. The ether layer is dried over anhydrousijsodium sulfate and the ether removed by distillation at reduced pressure and 68 parts of otho-cresyl hydracrylate (B. P. 83 to 84 C./0.1 mm.) are obtained. A second fraction consists of beta-(carbo-o-cresoxy) ethyl hydracrylate.

Example V Example IV is repeated except that m-cresol is substituted for o-cresol. A 41.3% yield of mcresyl hydracrylate (B. P. 84 to 85 C./0.1 mm.) is obtained. Beta-(carbo-m-cresoxy) ethyl hydracrylate is also obtained.

Example VI Example IV is repeated substituting p-cresol for o-cresol. 46.5% of p-cresyl hydracrylate (B. P. 83 to 85" C./0.1 mm.) is obtained. Asecond fraction consists of beta-(carbo-p-cresoxy) ethyl hydracrylate.

Example VII Example I is repeated substituting betabutyrolactone for beta propiolactone. On distillation of the product a colorless oil, the phenyl ester of beta-hydroxy butyric acid is secured as a first fraction and another colorless oily material resulting from self-alcoholysis of this material is secured as a second fraction. The yields are good but not so high as in Example I.

As has been indicated hereinabove, the aryl hydnacrylates, the beta-(carbaroxy) alkyl hydracrylates and the other aromatic esters of betahydroxy carboxylic acids, are all very valuable chemical compounds. For example, they are useful as solvents and plasticizers for resinous and rubbery materials such as cellulose derivatives, vinyl resins, synthetic rubber and the like. The aryl hydracrylates are especially useful in that they may be heated in the presence of a dehydrating agent, whereupon a molecule of water is removed to form the corresponding acrylates which are useful polymerizable materials. In addition, the new compounds of ths invention may be used as chemical intermediates and for many other purposes.

Numerous modifications and various of the invention will be obvious to those skilled in the art and are included within the spirit and scope of the appended claims. r

I claim:

1. The method which comprises reacting a phenol of the formula ArOH wherein Ar is an aryl hydrocarbon radical, with a beta-lactone of wherein each R is a member of the class consisting of hydrogen and lower alkyl radicals such atoms, in the presence of a strong mineral acid catalyst and recovering a compound of the formula wherein n is a numeral, including zero, less than two and-Ar and each B have the same meaning as above. I

2. The method which comprises reacting a phenol of the formula ArOI-I wherein Ar is an aryl hydrocarbon radical,- with beta-propiolactone in the presence of a strong mineral'acid catalyst and recovering a compound of the formula wherein n is a numeral, including zero, less than two and Ar has the same meaning as above.

3. The method which comprises reacting a phenol of the formula ArOH, wherein Ar is an aryl hydrocarbon radical with beta-propiolactone in the presence of a strong mineral acid catalyst and recovering a compound of the formula fig/11H /HH /HH\ H Ar0(|fO- OOO OC0H wherein Ar has the same meaning as above.

4. The method which comprises reacting a phenol of the formula ArOI-I, wherein Ar is an aryl hydrocarbon radical, with beta-propiolactone in the presence of a strong mineral acid catalyst, and recovering a compound of the formula wherein Ar has the same meaning as above.

5. The method which comprises reacting phenol and beta-propiolactone in the presence of a strong mineral acid catalyst and recovering phenyl hydracrylate.

6. The method which comprises reacting phenol and beta-propiolactone in the presence of a strong mineral acid catalyst and recovering beta- (carbophenoxy) ethyl hydracrylate.

7. The method which comprises reacting orthocresol with beta-propiolactone in the presence of a strong mineral acid catalyst and recovering ortho-cresyl hydracrylate.

8. The method which comprises reacting phenol with beta-propiolactone at a temperature of from 40 C. to 60 C. and in the presence of a sulfuric acid catalyst, and distilling the reaction product to recover phenyl hydracrylate and beta- Kcarbophenoxy) ethyl hydracrylate.

9. A new chemical compound of the formula R R R RR R it it wherein Ar is an aryl hydrocarbon radical, each R is a member of the class consisting of hydrogen and lower alkyl radicals such that each R RR R structure contains from 3 to 6 carbon atoms, and n is a numeral, including zero, less than two.

10. Anew chemical compound of the formula ArOC-CH2CH2OH ('5 wherein Ar is an aryl hydrocarbon radical.

11. A new chemical compound of the formula Ar-O(IT-CHz-CHz-Ofi3-OHz-CH2-OH wherein Ar is an aryl hydrocarbon radical. m

12. As a new chemical compound phenyl hydracrylate of the formula OfiCH2-CH2OH 13. vAs a new chemical compound beta-(carbophenoxy) ethyl hydracrylate of the formula 14. As a new chemical compound ortho-cresyl hydracrylate of the formula WARREN L. BEEARS.

No references cited. 

1. THE METHOD WHICH COMPRISES REACTING A PHENOL OF THE FORMULA AROH WHEREIN AR IS AN ARYL HYDROCARBON RADICAL, WITH A BETA-LACTONE OF THE FORMULA 